1. Field
Embodiments relate to recovery from failure of primary storage volumes by using mirrored data maintained with host timestamps.
2. Background
Certain types of data mirroring provide data replication over extended distances between two sites for business continuity and disaster recovery. Such data mirroring may provide a recovery point objective (RPO) of as low as 1-5 seconds or less between the two sites at extended distances with marginal or no performance impact on the application at the primary site. Such mirroring replicates the data asynchronously and also forms a consistency group at a regular interval allowing a clean recovery of an application.
In certain situations, such mirroring may be achieved via a combination of asynchronous remote copy over the extended distances and point in time copy. In asynchronous remote copy storage volumes are copied from a primary storage controller to a secondary storage controller asynchronously. Once consistency groups are formed during the asynchronous remote copy, a point-in-time copy operation is performed in the secondary storage controller. A point-in-time copy is a fully usable copy of a defined collection of data that contains an image of the data as it appeared at a single point-in-time. The copy is considered to have logically occurred at that point-in-time. Implementations may perform part or all of the copy at other times as long as the result is a consistent copy of the data as it appeared at that point-in-time.